Patent GB-373820-A (GB)
Title: Improvements in and relating to swivelling joints adapted for use on camera tripods,gun mountings and the like
IPC: F16M11/12
Filed: 1931-07-03
Abstract: 373,820. Stands. ALLEN, R. and ALLEN, K., Chiltern Rise, Woodcote, Oxfordshire. July .3, 1931, No. 19219. [Class 52 (v).] In a universal joint for a camera tripod head or a gun mounting, of the kind having clamping means operated by a long handle which serves to direct the apparatus mounted when the joint is unlocked, the control handle is in the form of a spindle mounted in bearings on the movable part of the joint, and carries a cam which serves to lock the joint when the handle is turned in its bearings. The joint may be a ball joint or may comprise two separate pivotal connections with axes at right-angles ; in the latter case the control handle preferably locks only the pivot with a horizontal axis, a separate locking means being provided for the other pivot, although the control handle may be used to direct either the tipping or the swivelling movement or both when the appropriate locking means are released. Fig. 2 shows a joint comprising two separate pivots; a shallow cup 15, with a central pivot, is fixed by a central screw to the top of the tripod or other stand, and a disc 19 pivots in this cup ; the disc carries a double conical boss 21, and on this boss rotate two caps 31, 32, the cap 31 carrying an upper part 33 provided with a socket in which a stud 45 on the camera or other apparatus can be clamped. The disc 19 is kept in engagement with the member 15 by cover-plates 24 engaging a groove in the central pivot. One half of the disc 19 is weakened by holes and saw-cuts, as shown in Fig. 5, so that it is resilient and can be expanded to grip the walls of the cup, to prevent rotation, by a conical-headed screw 27 which is tightened by a hand-nut; the screw 27 is adjusted through hole in the base of the cup 15, and is held against rotation by a grub screw engaging one of a number of notches in its head. The conical caps 31, 32 are fixed together by screws 34 in a manner permitting slight yielding to an axial direction, and a clamping spindle 35, non-rotatable in the caps, passes freely through the conical bosses 21 ; one end of the spindle is forked and is bored transversely and provided with bearings to receive a rotatable :control spindle 37 on which is fixed a cam 38 engaging a ball to press a cotter 41, when the control spindle is turned, so as to clamp the two caps 31, 32 on the bosses 21. In a modification, the disc 19 carries two fixed caps similar to 31, 32, while two separate conical bosses, connected in a similar manner to that shown for the caps in Fig. 2, bear inside the caps and.are pressed into engagement therewith by a double-acting cam between them carried and operated in a manner similar to that shown. The upper part 33 of the mounting is split, as shown in Fig. 4, so as to be contracted round the stud 45 on the apparatus by a spindle 52 which is tightened by a cotter 55 operated by a cam handle 53 carried in a forked end of the spindle 52. Alternatively, the part 33 is not split, but the spindle 52 is provided with a face inclined to its axis to engage the grooved periphery of the stud 45; the spindle is withdrawn from engagement by a spring. Fig. 11 shows an arrangement employing a ball joint, in which the base member of the mounting carries a half ball 83 in which an upper half ball 84 is rotatably mounted. Caps 88, 89 corresponding to 31, 32 of Fig. 2 embrace the ball and are forced to grip it by the clamping mechanism already described. The clamping spindle 90 passes through the upper half of the ball only. In a modified form, Fig. 9, the ball is in one piece, and the clamping spindle passes above it; the ball is formed with a circumferential groove in which engage balls 70 set in the caps. Fig. 9 also shows a modified form of clamp for the stud 45, comprising a lever 79 pivoted in the part 77, with a camshaped part which engages the groove of the stud 45; the lever is held in its unlocked position by a spring-pressed ball 80 entering a depression in it, and is pressed towards the locking position by a spring (not shown) acting through a roller on the cam surface of the lever. Instead of fixing the mounting on its stand by a screw as in Figs. 2 and 9, an ordinary split socket with hand-clamping screw engaging a stud on the stand may be used as in Fig. 11. This form of clamp may also be used to attach the apparatus to the mounting in place of the clamp shown in Fig. 4.